/* See LICENSE for licensing and NOTICE for copyright. */
package org.ldaptive.asn1;

import java.nio.ByteBuffer;

/**
 * Converts booleans to and from their DER encoded format.
 *
 * @author  Middleware Services
 */
public class BooleanType extends AbstractDERType implements DEREncoder
{

  /** Boolean true byte representation. */
  private static final byte TRUE_BYTE = (byte) 0xff;

  /** Boolean false byte representation. */
  private static final byte FALSE_BYTE = (byte) 0x00;

  /** Boolean to encode. */
  private final byte[] derItem;


  /**
   * Creates a new boolean type.
   *
   * @param  item  to DER encode
   */
  public BooleanType(final boolean item)
  {
    super(UniversalDERTag.BOOL);
    derItem = toBytes(item);
  }


  /**
   * Creates a new boolean type.
   *
   * @param  tag  der tag associated with this type
   * @param  item  to DER encode
   *
   * @throws  IllegalArgumentException  if the der tag is constructed
   */
  public BooleanType(final DERTag tag, final boolean item)
  {
    super(tag);
    if (tag.isConstructed()) {
      throw new IllegalArgumentException("DER tag must not be constructed");
    }
    derItem = toBytes(item);
  }


  @Override
  public byte[] encode()
  {
    return encode(derItem);
  }


  /**
   * Converts bytes in the buffer to a boolean by reading from the current position to the limit.
   *
   * @param  encoded  buffer containing DER-encoded data where the buffer is positioned at the start of boolean bytes
   *                  and the limit is set beyond the last byte of integer data.
   *
   * @return  decoded bytes as a boolean.
   */
  public static boolean decode(final ByteBuffer encoded)
  {
    final byte[] bytes = readBuffer(encoded);
    if (bytes.length > 1) {
      throw new IllegalArgumentException("Boolean cannot be longer than 1 byte");
    }
    if (bytes[0] == TRUE_BYTE) {
      return true;
    } else if (bytes[0] == FALSE_BYTE) {
      return false;
    } else {
      throw new IllegalArgumentException("Invalid boolean value: " + (int) bytes[0]);
    }
  }


  /**
   * Converts the supplied boolean to a byte array.
   *
   * @param  b  to convert
   *
   * @return  byte array
   */
  public static byte[] toBytes(final boolean b)
  {
    return new byte[] {b ? TRUE_BYTE : FALSE_BYTE};
  }
}